class MyCircularQueue {

    private int[] elem;
    private int front; // 队头指针
    private int rear; // 队尾指针

    public MyCircularQueue(int k) {
        this.elem = new int[k+1];
    }
    
    public boolean enQueue(int value) {
        if(isFull()) {
            return false;
        }
        this.elem[rear] = value;
        rear = (rear + 1) % elem.length;
        return true;
    }
    
    public boolean deQueue() {
        if(isEmpty()) {
            return false;
        }

        front = (front + 1) % elem.length;
        return true;
    }
    
    public int Front() {
        if (isEmpty()) {
            return -1;
        }
        return elem[front];
    }
    
    public int Rear() {
        if (isEmpty()) {
            return -1;
        }
        int index = (rear == 0) ? elem.length - 1 : rear -1;
        return elem[index];
    }
    
    public boolean isEmpty() {
        return front == rear;
    }
    
    public boolean isFull() {
        return (rear + 1) % elem.length == front;
    }

    public static void main(String[] args) {
        MyCircularQueue myCircularQueue = new MyCircularQueue(3);
        myCircularQueue.enQueue(1);
        myCircularQueue.enQueue(2);
        myCircularQueue.enQueue(3);
        myCircularQueue.enQueue(4);
        myCircularQueue.Rear();
    }
}